experimental method and variables

• extraneous variables

  a variable under study that is not the independent variable but may affect the dependant variable. this makes the outcome meaningless.
• confounding variables

  can provide an alternative explanation for your result. they are difficult control.
• internal validity


  concerned with what goes on inside a stuy, to gain this they must design the research carefully, controlling confounding and extraneous variables, ensuring that they are testing what they intend to test.
• external validity

  affected by internal validity, you cannot generalise the results of a study that was low in internal validity because the results have no real meaning.

  ecological validity- the place where the research was conducted may not be appropriate to generalise from real life/ other settings.

  population validity- if researchers only use men, you cannot generalise to women.

  historical validity- if it was conducted in the past it may not be appropriate to generalise findings to people today.
• demand characteristics

  cue that makes participants unconsciously aware of the aims of the study, so then change their behaviour.

  pleaseUeffect- please the experimenter

  screwUeffect- deliberately underperforming.
• single blind design

  participants are not aware of the research aims.
• standardisation

  using the same formalised procedures and instructions for all participants in a research study in order to repeat it.
• mundane realism


  refers to how the study mirrors the real world. if the study is too artificial then the participants wont act as they normally do.
• generalisation

  to be able to generalise the results beyond the unique research setting so we can understand behaviour in everyday life.
• independant variable

  aspect of the situation that is manipulated by the researcher, so the effect of the dependent variable can be measured.
• dependant variable

  variable that is measured by the researcher, any affect on the dependant variable should be caused by the independent variable.
•  independent variable

  The independent variable is the one the experimenter manipulates, it is assumed to have a direct effect on the dependent variable.
• dependent variable

  • The dependent variable is the thing being measured, or the results of the experiment.
• demand characteristcs

  Demand characteristics are a type of extraneous variable that occurs if the participants work out the aims of the research study, they may begin to behave in a certain way.

  For example, in Milgram’s research, critics argued that participants worked out that the shocks were not real and they administered them as they thought this was what was required of them. 

  Extraneous variables must be controlled so that they do not affect (confound) the results.
• Lab Experiments

  Lab Experiments are conducted in a well-controlled environment, not necessarily a laboratory, and therefore accurate and objective measurements are possible. The researcher decides where the experiment will take place, at what time, with which participants, in what circumstances,  using a standardized procedure.
• Field experiments 

  • Field experiments are conducted in the everyday (natural) environment of the participants. The experimenter still manipulates the IV, but in a real-life setting. It may be possible to control extraneous variables, though such control is more difficult than in a lab experiment.